Water-soluble films are useful in many applications. In the household and industrial markets, the use of water-soluble films in detergent packets, such as unit dose delivery systems, provides several benefits for consumers including ease and convenience of use, low cost, and increased safety as a result of a reduction in exposure to chemicals present in cleaning formulations. Much of the art of packaging unit dose detergents relates to the development of the water-soluble film package. Presently, the pouch or package containing the liquid laundry detergent is predominantly based on partially hydrolyzed polyvinyl alcohol homopolymers, PVOH, and its copolymers.
Liquid laundry detergent compositions are usually formulated with high water content, e.g., of about 70 to 90 wt % of water. High water content provides several advantages, including faster delivery and dispersibility of the formulation ingredients. However, PVOH based polymers are unsuitable for packaging liquid laundry detergent compositions with water content greater than 15-20%. Higher water content will destroy the structural integrity of the water soluble pouch due to plasticization and premature dissolution and breakdown of the film.
Current unit dose liquid laundry detergents packaged in PVOH-based water dispersible pouch or packets are therefore highly concentrated heavy-duty liquid formulations with low levels of water content. In these formulations, the water content is typically limited to about 10 wt % to ensure compatibility of the liquid detergent with the water dispersible pouch and prevent premature dissolution and breakdown of the pouch. Because of the low water content, liquid unit dose systems require higher amounts of organic solvents compared to their liquid laundry detergents counterparts. These solvents unfortunately add cost to the detergent formulation without providing any additional cleaning benefit.
The problem addressed by this invention is the provision of water-soluble films and packets or pouches for liquid laundry formulations that contain high water content, for instance, of 20% by weight or more.